[en] Photoinduced charge injection from a perylene dye molecule into the conduction band of a TiO₂ system decorated by a metal nanoparticles (MNP) is studied theoretically. Utilizing the density matrix theory the charge transfer dynamics is analyzed. The continuous behavior of the TiO₂ conduction band is accounted for by a Legendre polynomials expansion. The simulations consider optical excitation of the dye molecule coupled to the MNP and the subsequent electron injection into the TiO₂ semiconductor. Due to the energy transfer coupling between the molecule and the MNP optical excitation and subsequent charge injection into semiconductor is strongly enhanced. The respective enhancement factor can reach values larger than 10³. Effects of pulse duration, coupling strength and energetic resonances are also analyzed. The whole approach offers an efficient way to increase charge injection in dye-sensitized solar cells.

[en] Exploring the relationship between surface urban heat island (SUHI) effect and urban economic development is a problem that people pay attention to for a long time. In this paper, we use MODIS surface temperature data to calculate the SUHI intensity of 34 major cities in mainland China from 2003 to 2017. Then we first analyze the relationship between annual average SUHI intensity and urban annual gross domestic product (GDP). A good linear relationship is found in most cities in north and northeast China with the coefficient of determination (R²) reaching 0.63 at most. In addition, the relationship between SUHI intensity and GDP during the day is significantly better than that at night. These conclusions can provide a new insight for people to understand the impact of urban heat island effect on urban economic development in the future. (paper)

[en] In this paper, we described a simple growth-doping approach for aqueous synthesis of Cu-doped ZnSe quantum dots (Cu:ZnSe d-dots) with mercaptopropionic acid as stabilizer. The influences of the ratios of precursors and the concentration of Cu dopant ions on Cu:ZnSe d-dots synthesis were studied in detail in this study. The Cu dopant ions had significant influence on the optical properties of ZnSe d-dots. The bandgap emission of ZnSe was effectively restrained through Cu doping. The prolonged reflux facilitates the doping of Cu, which led to the red-shift of the emission of Cu:ZnSe d-dots from 465 to 495 nm. The stable Cu:ZnSe d-dots with high quality can be obtained under optimal conditions. As compared with cadmium-based nanocrystals synthesized in aqueous solution, Cu:ZnSe d-dots have much lower toxicity, indicating that they can be applied as outstanding fluorescent labels for biological assays, imaging of cells and tissues, even in vivo investigations. - Highlights: → We describe a simple growth-doping approach for aqueous synthesis of Cu:ZnSe d-dots. → The emission of Cu:ZnSe shifts from 465 to 495 nm with the prolonged reflux. → As compared with cadmium-based nanocrystals, Cu:ZnSe d-dots have much lower toxicity. → Cu:ZnSe d-dots can be utilized in the fields of multiform biomedical applications.

[en] Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is widespread but scattered, and the pressure, flow-rate and nitrogen content of CBM feed vary significantly. The skid-mounted liquefaction device is suggested as an efficient and economical way to recover methane. Turbo-expander is one of the most important parts which generates the cooling capacity for the cryogenic liquefaction system. Using turbo-expander, more cooling capacity and higher liquefied fraction can be achieved. In this study, skid-mounted CBM liquefaction processes based on Claude cycle are established. Cryogenic turbo-expander with high expansion ratio is employed to improve the efficiency of CBM liquefaction process. The unit power consumption per liquefaction mole flow-rate for CBM feed gas is used as the object function for process optimization, compressor discharge pressure, flow ratio of feed gas to turbo-expander and nitrogen friction are analyzed, and optimum operation range of the liquefaction processes are obtained. (paper)

[en] The use of fullerene [60] (C₆₀) as carbon support material for the dispersion of catalysts, which provides new ways to develop the advanced electrocatalyst materials for its distorted structure. In this article, polyaniline (PANI)-modified C₆₀ (abbreviated as PANI-C₆₀) is introduced, and the platinum–ruthenium alloy nanoparticles are successfully supported on PANI-C_60. According to the transmission electron microscopy measurements, the average particle size of the as-prepared nanoparticles dispersed on PANI-C₆₀ is 2.4 nm. Electrochemical studies reveal that the Pt-Ru/PANI-C₆₀ nanocomposites show excellent electrocatalytic activity toward methanol oxidation, showing that the PANI-C₆₀ may be a better potential candidate to be used as the supports of catalyst for electrochemical oxidation

[en] Highlights: • We identified and characterized GmMYB3a of R2R3 myeloblastosis repressor family. • GmMYB3a is induced by various abiotic stresses. • For this study, we used a transgenic soybean over-expressing GmMYB3a. • We evaluated the photosynthesis index under salt-alkali treatments. • GmMYB3a was found to negatively affect the response of plants to salt stress. Myeloblastosis (MYB) transcription factor (TF) plays a positive role in the growth and stress response of plants; however, information on the functions of MYB repressors in soybean is limited. In the present study, the gene GmMYB3a was identified and characterized as a member of the R2R3 MYB repressor family, which is induced by various abiotic stresses. To understand the functions of GmMYB3a, a transgenic soybean over-expressing GmMYB3a was obtained and the photosynthetic index under salt–alkali treatments was evaluated. The transgenic line exhibited a series of negative regulation relative to the wild-type control. Quantitative real time polymerase chain reaction revealed that the physiological parameters, including soluble sugar, free proline, and chlorophyll contents; and photosynthetic rate decreased in the transgenic plants. Furthermore, GmMYB3a overexpression down-regulated a set of key genes associated with plant defense signal pathways. These finding suggest that GmMYB3a negatively affects the response of plants to salt stress.

[en] Highlights: ► Preparation of three kinds of water-soluble QDs: CdTe, CdTe@SiO₂, Mn:ZnSe. ► Evaluated the cytotoxicity qualitatively and quantitatively. ► Fluorescent staining. ► Detected the total intracellular cadmium in cells. -- Abstract: Quantum nanoparticles have been applied extensively in biological and medical fields, the cytotoxicity of nanoparticles becomes the key point we should concern. In this paper, the cytotoxicity of three kinds of water-soluble nanoparticles: CdTe, CdTe@SiO₂ and Mn:ZnSe was studied. We evaluated the nanoparticles toxicity qualitatively by observing the morphological changes of human osteoblast-like MG-63 cells at different incubation times and colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were carried out to detect the cell viability quantitatively. The results showed that CdTe nanoparticles with high concentrations caused cells to die largely while CdTe@SiO₂ and Mn:ZnSe nanoparticles had no obvious effect. For further study, we studied the relation between the cell viability and the total cadmium concentration in cells and found that the viability of cells treated with CdTe@SiO₂ nanoparticles was higher than that treated with CdTe nanoparticles. We also discovered that the death rate of cells co-incubated with CdTe nanoparticles was proportional to the total intracellular cadmium concentrations.

[en] The introduction of oxygen vacancies (O_v) in TiO₂ has significant effects on improving the light absorption capacity, expanding the light absorption range and inhibiting photo-generated charge recombination. Here, we used hydrochloric acid and urea mixed with TiO₂ hierarchical micro-nanospheres (THS) followed by annealing in an air atmosphere to dope THS with nitrogen and successfully mediated the formation of oxygen defects. Then, the Ni-based promoter is supported on the THS with oxygen vacancy defects by impregnating the metal ions in the solution. Compared with untreated Ni-THS, Ni-THS(O_v) modified by oxygen deficiency has a shorter band gap and photo-generated charge separation efficiency, and its photocatalytic water splitting capacity was also significantly improved. The hydrogen production performance of Ni-THS(O_v) (0.1 wt%) reached 4.88 mmol g^-1 h^-1 under full-spectrum (UV-vis) irradiation. The synergistic relationship between THS, surface oxygen vacancies and the supported Ni promoters was further investigated. (authors)

[en] Highlights: • Off-design prediction iterative loop is complied to estimate turbine performance. • Well-established loss correlations in turbine are applied in meanstream line method. • Thermodynamic performance of a cryogenic turbo-expander is measuremented. • Validation of test result against turbine performance prediciton shows good agreement. Cryogenic turbo-expander is most significant equipment to provide cooling energy in system and its working condition is always deviated from design point. A mathematic prediction method study is carried out to estimate turbo-expander off-design performance. Computational iterative loop is compiled by Matlab, dimensionless mass flow rate equation of mean streamline and novel loss correlation are applied to quantitatively describe the flow expansion through turbine ducts. Cryogenic turbo-expander performance is evaluated by total-to-static efficiency. According to velocity ratio, the effect of pressure ratio, inlet temperature, rotational speed variation to turbine performance is analyzed, and the predicted performance map is plotted. Meanwhile, an experimental study is conducted under off-design condition. Temperature, pressure, rotation speed and volume flow rate are collected, total-to-static efficiency are calculated from turbine inlet and outlet states over pressure ratio range of 2.4–3.4, and the tested rotation speed range is set from 52,000 to 60,000 rpm. Turbine efficiency in different pressure ratio range are categorized and plotted with velocity ratio to validate against computational predicted characteristic. With experimental comparison, this off-design performance mathematic code can predict turbine real operation well.